Modify error message

:Release Notes:
PmLogString() give message id when json parsing is failed.

:Detailed Notes:
PmLogString() does not give message id when the json parsing
is failed for key-value pairs.

:Testing Performed:
Compiled locally and tested on local and TV.
Verified in the log file, error text displayed in
/var/log/messages properly.

:QA Notes:

:Issues Addressed:
[GF-13240] pmloglib: INVALID_JSON does not give message id

Open-webOS-DCO-1.0-Signed-off-by: Hongjeon Ha <hj.ha@lge.com>

Change-Id: I4327e9b76ba09f86a174cd72186ed633cc78164a
Reviewed-on: https://g2g.palm.com/3078
Reviewed-by: Build Verification
Reviewed-by: Hongjeon Ha <hj.ha@lge.com>
Tested-by: Hongjeon Ha <hj.ha@lge.com>
Reviewed-by: Gayathri Srinivasan <gayathri.srinivasan@lge.com>